Long-term evolution and non-stationary behaviours of daily and subdaily precipitation extremes in China

The rise of extreme precipitation events has attracted wide attention throughout the world. However, the analysis of precipitation extremes is not sufficient in the short period of instrumental observation and it is complicated by their non-stationary behaviours. As a period dominated by natural forcing, the last millennium is helpful for understanding long-term changes in precipitation extremes. Therefore, this study aimed to (1) investigate changes in daily and subdaily precipitation extremes in China from the last millennium to the end of the twenty-first century, (2) detect the non-stationarity of precipitation extremes and (3) compare design storms by using stationary and non-stationary distributions. The annual maximum 1-day precipitation (RX1day) and annual maximum 3-hour precipitation (RX3hour) are used to quantify variations of precipitation extremes. The results show that the trend of RX1day was insignificant for the Medieval Climate Anomaly (MCA, 950-1250) and the Little Ice Age (LIA, 1500-1800). For the historical period (1850-2014), the trend of RX1day and RX3hour was insignificant in most subregions. In addition, the differences for RX1day between the historical period and the MCA/LIA were mostly in the range of -5% to 5%. For the future period (2015-2100), RX1day and RX3hour are projected to increase in almost all land grids compared with the historical period, and they show greater increases in western China than eastern China. The non-stationarity of RX1day and RX3hour is mainly found under the high-emission scenario. Moreover, stationary generalized extreme value (GEV) distribution underestimates 50-year return levels for RX1day and RX3hour in most areas compared with non-stationary GEV distribution under the high-emission scenario. Overall, this study suggests that daily and subdaily extreme precipitation will intensify over China in the future. For design storms, non-stationary methods need to be used for risk management and engineering design under the high-emission scenario. The stationary generalized extreme value (GEV) distribution underestimates 50-year return levels of daily and subdaily extreme precipitation in most areas of China compared with non-stationary GEV distribution under the high-emission scenarios.image